Engine starter



Patented Dec. 27, 1938 UNITED STATES PATENT OFFICE ENGINE STARTERHerbert L. Meeder, Denver, Colo.

Application February 21, 1938, Serial No. 191,652

5 Claims.

This invention relates to improvements in engine starters of the generaltype shown and claimed in U. S. Letters Patent No. 1,889,995, granted tome on December 6, 1932.

The type of engine starters to which the invention relates comprises amotor driven shaft that extends across a fly wheel whose outer peripherycarries a ring gear. Attached to the shaft by means of a helical springis a sleeve that is so mounted that it may rotate thereon. A pinion isattached to the sleeve by a threaded means that forces the pinion tomove along the axis of the shaft whenever it rotates relative to thesleeve. The parts are so adjusted that the pinion is normally out ofmesh with the ring gear but whenever the shaft and sleeve are suddenlyrotated the inertia of the pinion prevents it from starting as quicklyas the motor actuated shaft and sleeve and this lag produces a relativerotation of the pinion and the sleeve which results in an axial movementof the pinion that carries it into operative engagement with the ringgear.

If the pinion happens to engage the ring gear in such a way that itsteeth can enter between those ofthe ring gear no trouble results butthere is always an equal chance that the teeth of the pinion will strikethe teeth of the ring gear; when this happens the forward movement ofthe pinion is stopped and the wedge action of the threaded connectionforces the pinion against the ring gear teeth and stops the'motor. Wenow have what is commonly called a starter lock.

Many expedients have been tried and employed for the purpose ofpreventing the formation of such starter locks, the most commonexpedient being the tapering of the pinion teeth.

One of the objects of this invention isto produce an engine starter, ofthe type indicated, that shall be of very simple and yet of substantialconstruction but which is composed of the minimum number of parts.

Another object is to produce a starter that can be constructed at aminimum of expense and which can be assembled and taken apart veryeasily.

A further object is to produce an engine starter that will automaticallyrelease itself if a starter lock is formed so that it will alwaysoperate even if the teeth on the pinion first strike the ends of theteeth on the ring gear.

A still further object is to produce an improved connecting means forthe starter spring that permits the spring to be easily constructed andreadily applied and removed.

Another object is to produce a spring and means for attaching it toother parts of the device in such a way that there is no lost motionbetween the spring and the parts to which it is attach-ed; and

Another object is to so construct the sleeve and the pinion that theycan be connected and disconnected without the use of tools.

The above and any other objects that may become apparent as thedescription proceeds are attained by means of a construction and anarrangement of parts that will now be described in detail, reference forthis purpose being had to the accompanying drawing in which the inventiohas been illustrated and in which:

Figure, l is a longitudinal section through the assembly and shows theparts in their relative position when a starter lock has occurred andjust before it is released.

Figure 2 is a View partly in section showing the manner in which thesleeve and the pinion are connected and disconnected;

Figure 3 is an end view of the sleeve shown in Fig. 2;

Figure 4 is a side elevation of the helical starter spring; and

Figure 5 is an end view of the spring.

In the drawing numeral l0 designates a drive shaft which is journaled ina bearing II, that may be one bearing of the starter motor, which hasnot been shown. The shaft extends transversely of the fly wheel I2 whichis provided with a ring gear I3 that has gear teeth M. Attached to theshaft, adjacent the front end of the bearing II is a sleeve I5 having aflange I 6. In the drawing the flange has been shown eccentric but itmay be concentric with the shaft. The flange is preferably located atthe middle point of the sleeve, but this is a matter of choice only.Sleeve [5 is secured to the shaft by means of a threaded pin I! thatextends beyond the outer surface and is perforated for the reception ofa cotter pin l8 that engages the surface of the flange and holds the pinfrom rotating.

The flange is provided with a hole 19, to which reference willhereinafter be made.

Another and longer sleeve 20 is mounted on the shaft for relative rotaryand longitudinal movement. This sleeve has an eccentric flange 2|,similar to flange 16, which is provided with a hole 22.

A helical compression spring 23 is positioned between flanges l6 and 22and this spring has its ends offset in the manner indicated in Fig. 4,from which it will be seen that near its ends the spring has been bentso that a portion marked 24 extends in the direction of the length ofthe spring. The length of the bent portion is slightly greater than thethickness of the flanges and when the parts are assembled, parts 24 arein the holes 19 and 22. The ends 25 of the spring are bent so that theyare inclined towards the middle of the spring as indicated by dottedlines 26. When the sleeves l5 and 20 are detached from the shaft theends of the spring can be inserted and removed from the openings in theflanges. When the sleeves are in place on the shaft the ends 25 engagethe sides of the flanges and this puts the spring under a slight bendingstrain that prevents it from having lost motion with respect to theflanges.

In Fig. 1 the spring is shown fully compressed and in this position ofthe parts the adjacent ends of the sleeves are separated by a space a.When the parts are in normal inoperative position flange 2| occupies thedotted line position to the right of the full line position, thedisplacement represents the amount the spring has been compressed. Innormal inoperative position the pin 21 is adjacent the other end of theslot 3|.

It will be observed that sleeve 29 is longer than sleeve 15 and that theflange 2| is positioned closer to its inner end than to its outer end,in fact flanges l6 and 2! may be flush with the inner ends of thesleeves which are merely hubs. However, since nothing is gained bypositioning the flanges nearer the inner ends of the sleeves than thatshown, that construction is preferred. Sleeve 20 extends a considerabledistance towards the end of the shaft and is provided with a pin 21. Theouter end of sleeve 29 is shorter on one side of a diameter than on theother and the shorter side is diametrically opposite from the pm.

A pinion 28, which is provided on one side with an elongated hub 29, hasa central opening of two difierent diameters, that portion to the leftin the drawing has an opening of such size that it can receive the endof sleeve 26 and the outer end has an opening 30 of the same diameter asthe shaft I U. The hub 29 has a helical slot 3| through which pin 2'!extends. The slot terminates near the inner end of the hub so that thehub can be applied to and removed from the sleeve by a movement likethat illustrated-in Fig. 2. After the hub 29 and sleeve 20 have beenassembled on the shaft so as to form an assembly like that shown in Fig.2 they are ready to function. If the hub is now rotated on the sleeveuntil a tooth on the pinion engages the end of a tooth on the ring gearand if the shaft is then turned so as to produce further relativerotation between the sleeve and the hub the spring will be compresseduntil the parts assume the position shown in Fig. 2. If the pinion isheld against rotation and the sleeve rotated relative thereto the pinwill soon reach the end of slot 3| and the resulting hammer blow willrotate the pinion relative to the ring gear and the spring will thenproject the pinion into operative position.

When the starting motor is started it produces a sudden turning of shaftIi] in the direction indicated by arrow 32 in Fig. 1. Since the pinionis free to turn on sleeve 20 its inertia will prevent it from rotatingand this will produce relative rotation between sleeve 20 and hub 29with the result that the pin will move in slot 3| and force the piniontowards the ring gear. If the teeth of the pinion strike the spacesbetween the teeth of the ring gear'the parts will assume the positionindicated by dotted lines and the fly wheel will be turned, therebycranking the engine. If, on the other hand, the teeth on the pinionstrike the teeth on the ring gear, further outward, movement of thepinion will be stopped but sleeve 20 will continue to rotate and willmove towards the left until the parts assume the position shown inFig. 1. Upon further movement pin 21 strikes the left end of the slot,whereupon the hammer blow of the pin, assisted by the momentum of therotating parts, will move the pinion relative to the ring gear until theteeth of the pinion reach the spaces between the teeth on the ring gearwhen the action of the. spring, which is now under compression, willforce the pinion outwardly and into mesh with the ring gear. See dottedline position in Fig. 1.

Attention is called to the fact that to obtain the action justdescribed, the adjacent ends of sleeves i5 and 29 must be free to movetowards each other a distance at least as great as the width of thepinion, and preferably as great as the maximum longitudinal movement 'ofthe pinion on sleeve 20, which distance is indicated by letter binFig. 1. It is apparent that if the opposing'ends of the sleeves comeinto engagement before the pin 21 reaches the end of slot 3|, the partswill become firmly wedged and there can be no automatic release. By soproportioning the parts that the pin 2? reaches the inner end of theslot before the sleeves come into contact with each other, the torqueaction exerted by pin 21 on the pinion will move the latter relative tothe ring gear and cause it to be forced into mesh with the latter. Thisrelationship of the parts is very important and results in an actionthat assures that any time the pinion teeth strike the ring gear teeththis will automatically be corrected, with the result that no starterlock will be formed.

In Fig. l the spring is shown fully compressed and the pin at the innerend of slot 31. Therefore, the hub can neither rotate nor movelongitudinally outward on the sleeve but the two must now rotatetogether.

Attention is also directed to the extreme simplicity of theconstruction, to the ease with which the pinion can be detached from andconnected with the sleeve and to the construction of the spring and itsmanner of attachment to the flanges.

The end of shaft l0 nearest the ring gear is considered as the outer endand whenever the terms outer and inner are employed they are used inthis sense.

In the device illustrated the relative longitudinal movement of thepinion and sleeve 20 is substantially equal to the length of the teethon the pinion, and the starter spring must be compressible a distance atleast as great as the length of the pinion teeth.

The slot 3| and pin 27 function in the manner of an ordinary thread toproduce relative longitudinal movement when sleeve 20 and hub 29 rotaterelative to each other, One important difference however is that ifordinary threads were used some additional means would have to beprovided to get the hammer blow efiect that is produced when pin 21strikes the inner end of slot 3!. An equivalent means, may, of course,be substituted for that shown and the pin and slot are merelyillustrative of means for this purpose. It will be observed that thedistance that sleeve 20 must travel in a direction to compress spring23, after the outward movement of the pinion is stopped by engagement ofthe teeth of the ring gear, depends on the length of slot 3| and itspitch because the release is effected by the sudden impact or hammerblow when pin 21 strikes the inner end of the slot. In actual practicedistance D is slightly greater than the length of the pinion teeth plusnecessary clearance but may be longer than this.

Having described the invention what is claimed as new 15-.-

1. In an engine starter of the type in which a ring gear engaging pinionis connected with a power shaft by means of a sleeve attached to theshaft-by a helical spring, the pinion and sleeve being interconnected bymeans comprising a helical slot, which is closed at its inner end, inone and a cooperating pin in the other, which produces relativelongitudinal movement of the pinion and the sleeve whenever they rotaterelative to each other, the sleeve being mounted for 1011- gitudinalmovement on the shaft, in a direction tochange the length of the spring,which movement in a direction to compress the spring is at least asgreat as the normal overlap of the teeth on the ring gear and thepinion.

2. In an engine starter having a power shaft, a sleeve carried therebyfor rotary and longitudinal movement, a flange rigidly secured to theshaft, a helical spring having one end attached to the flange and theotherto the sleeve, a pinion for engaging a ring gear, said pinionhaving an elongated hub, mounted on the sleeve for relative longitudinaland rotary movement, the hub having a helical slot which is closed atits inner end, a pin projecting radially from the sleeve and operativelyengaged in the slot, whereby when the pinion is rotated relative to thehub it will also move axially thereon, the sleeve having an inwardlongitudinal movement on the shaft, from normal non-tension position ofthe spring to tensioned position, at least as great as the normaloverlap of the teeth on the ring gear and the teeth of the pinion,whereby the sleeve can continue to rotate in the hub after the pinionhas engaged the end of a tooth on the ring gear and ceased to moveaxially of the shaft, until the pin engages the end of the slot andeflects a rotation of the pinion relative to the ring gear.

3. A motor driven engine starter for use with an engine having a gearconnected therewith, which is rotated by the engine, a power drivenshaft, parallel with the axis/of the gear and extending transverselythereof, a flange non-rotatably attached to the shaft, a sleeve carriedby the shaft and mounted for relative rotary and longitudinal movementthereon, said sleeve having a flange, a helical spring positionedbetween the flanges with its ends attached to the flanges, the sleeveextending beyond its flange on the side opposite from the spring, theend of the sleeve having a radial pin, a pinion having an elongated hubinto which the sleeve projects, the hub having a helical slot for thereception of the pin, the parts being so proportioned and adjusted thatwhen the spring is free from strain and the pinion is positioned as nearas possible to the flange on the sleeve the outer end of the pinion willbe spaced a short distance from the adjacent surface of the gear, thespring, the sleeve and the stationary flange will be so spaced that thespring can be compressed a distance at least as great as the distancethe teeth on the pinion overlap the teeth on the gear when the two arein operative engagement.

4. An engine starter of the type in which a driven pinion is projectedalong a shaft by means dependent on its inertia to move it into meshwith a starter gear carried by the engine, the starter comprising apower driven shaft, a flange attached to the shaft and held againstmovement relative thereto, a sleeve carried by the shaft'for both rotaryand longitudinal movement thereon, a flange integral with the sleeve, ahelical coil spring enclosing the shaft, between the flanges, the springhaving its ends attached to the flanges, the end of the sleeve oppositefrom the spring being shorter on one side of a diameterthan on theother, a pin extending radially from the longer side, a pinion having anelongated hub, rotatably encircling to the sleeve, the hub having ahelical slot for the reception of the pin, the parts being soproportioned that the spring can be compressed a distance slightlygreater than the normaloverlap of the teeth on the pinion and thestarter gear.

5. A sub-combination of an engine starter comprising a sleeve having aflange at one end, the other end of the sleeve being shorter on one sideof a diametrical plane than on the other, the longer side having aradial lug, a pinion having an elongated hub provided with a helicalslot for the reception of the lug, the position of the slot, the lengthof the lug and the difference in the length of the sleeve on oppositesides of the diametrical plane being so proportioned that the sleeve canbe inserted in and removed from the hub by a tilting movement.

HERBERT L. MEEDER.

